Bits that are used in mining and for removing road surfaces are typically mounted in a machine having a power driven cutter wheel. The wheel has an array of cutter bits mounted on the rim which attack the material to be broken.
It is desirable to have the bits rotate in their sockets to permit wear on the bit to be distributed evenly so as to maintain sharpness.
U.S. Pat. No. 4,149,753 describes a cutter bit having a shank with a reduced diameter held in a bore by a bearing ring. A compressible locking ring surrounds and grips the bearing ring so that the locking ring frictionally engages the bore in the bit holder to restrain relative axial movement between the cutter bit and the holder. An exposed and of the bit shank projects rearwardly of the block and rotates relative to the block. Thus, cuttings and dust which might wedge between the block and shank act to hinder rotation.